Apparatus adapted for driving or braking a metallic band

ABSTRACT

A system for braking or driving a strip comprising a roller for receiving a strip, a shoe movable radially toward the roller in the region in which the strip is received, a system for injecting compressed air into a chamber in the shoe to urge the shoe away from the strip and a jack acting on the shoe to urge the same towards the roller. When compressed air is applied to the chamber and acts between the shoe and the strip, the strip is applied against the roller with a force equal to that exerted by the jack on the shoe, the compressed air forming a very thin fluid cushion and providing a very small clearance between the shoe and the strip to prevent rubbing of the shoe on the strip. An annular hollow joint of flexible material is secured to the shoe and surrounds the chamber into which the compressed air is introduced. The joint has an orifice which opens into the chamber so that when the chamber is pressurized by the compressed air, the joint will simultaneously be pressurized and inflated. A plurality of joints can be mounted on the shoe, each joint defining an individual chamber, each chamber having an associated valve for control of the feed of compressed air thereto.

United States Patent 91 Gay [ Dec. 16, 1975 [54] APPARATUS ADAPTED FOR DRIVING OR BRAKING A METALLIC BAND [75] Inventor: Pierre Gay, La Tour En Jarez,

France [73] Assignee: Creusot-Loire Enterprises, Paris,

France [22] Filed: Jan. 7, 1975 [21] Appl. No.: 539,224

[30] Foreign Application Priority Data Jan. 11, 1974 France 74.00917 [52] US. Cl. 226/95; 226/195 [51] Int. Cl. B65H 17/28 [58] Field of Search 226/7, 95, 195; 242/752 [56] References Cited UNITED STATES PATENTS 3,231,163 1/1966 Chambers 226/95 3,724,735 4/1973 Gay 226/95 Primary Examiner-Richard A. Schacher Attorney, Agent, or Firm-Waters, Schwartz & Nissen 57 ABSTRACT A system for braking or driving a strip comprising a roller for receiving a strip, a shoe movable radially toward the roller in the region in which the strip is received, a system for injecting compressed air into a chamber in the shoe to urge the shoe away from the strip and a jack acting on the shoe to urge the same towards the roller. When compressed air is applied to the chamber and acts between the shoe and the strip, the strip is applied against the roller with a force equal to that exerted by the jack on the shoe, the compressed air forming a very thin fluid cushion and providing a very small clearance between the shoe and the strip to prevent rubbing of the shoe on the strip. An annular hollow joint of flexible material is secured to the shoe and surrounds the chamber into which the compressed air is introduced. The joint has an orifice which opens into the chamber so that when the chamber is pressurized by the compressed air, the joint will simultaneously be pressurized and inflated. A plurality of joints can be mounted on the shoe, each joint defining an individual chamber, each chamber having an associated valve for control of the feed of compressed air thereto.

8 Claims, 3 Drawing Figures US. Patent Dec. 16, 1975 Sheet1of2 3,926,353

& I

US. Patent Dec. 16, 1975' Sheet2of2 3,926,353

FIG=3 v 3 /MI.

APPARATUS ADAPTED FOR DRIVING OR BRAKING A METALLIC BAND FIELD OF THE INVENTION The present invention relates to improvements of ap paratus adapted to drive or brake a metallic band which has been described in US. Pat. No. 3,724,735.

BACKGROUND The aforesaid patent describes an apparatus for increasing the adherence of a metallic band on a drive roller or a brake roller. The apparatus comprises a shoe applied radially against the band in the region where it envelops the roller. The shoe is provided with an interior chamber fed with fluid under pressure which exerts a force applying the band against the roller. In order that the escape of fluid between the shoe and band is reduced to a minimum, the shoe is maintained as close as possible to the band by a jack which urges the shoe towards the band. The shoe is therefore'subjected to two opposing forces: i.e. the force of the jack which tends to apply it against theband'and the resultant force of the pressure of the flu'id'which-tends to space it therefrom. Theshoe therefore automatically positions itself such that leakage air between the shoe and band and therefore the distance between the shoe and band assumes a value such that the loss of fluid escaping by the leakage air produces'in the interior of the chamber a pressure which is in equilibrium with the force of the jack. Thus, direct contact between the shoe and the band is-prevented by the formation of a very thin cushion of the fluid which only provides a very small gap between the shoe and the band and which avoids all contact of the shoe with the band.

Several difficulties are nevertheless produced upon operation of the apparatus. Therefore it ,is necessary to provide mechanisms of great precision to satisfy the ,requirements of the operation, i.e. to ob tain a gap between the shoe and the band as small as possible so that the discharge of leakage fluid will be low while not pro.- viding any contact between the shoe and the band. Additionally, the bands concerned can have different thicknesses; however to obtain a minimum gap between the shoe and the band it is necessary for the radius of the cylindrical portion of the shoe to be equal to the radius of the roller plus the thickness of the band. The minimum gap can therefore only be obtained for a given thickness.

Additionally, under the effect of the fluid pressure, there is observed deformations which adversely effect the precision. Finally, the band itself often has planarity deficiencies so that in enveloping the roller it does not provide a perfectly cylindrical form, but rather it forms convexities more or less acentuated which must however pass without contacting the material of the shoe. As a result thereof it is necessary to increase the gap and consequently produce increase of the discharge of the fluid under pressure.

SUMMARY OF THE INVENTION An object of the present invention is to provide apparatus which avoids these disadvantages and compensates for the variations of thickness and of planarity of the band without increasing the leakage of fluid under pressure.

The invention is applicable to apparatus adapted to drive or to brake a metallic band by augmentation of the contact pressure of the band on a driven roller or a brake roller comprising a mobile shoe in a fixed frame fed with fluid under pressure and urged by a jack towards the band in a radial direction with respect to the roller. According to the invention, the edges of the interior chamber of the shoe facing the band are provided with a hollow tubular gasket or joint of flexible material communicating with the interior of the chamber. The feed of the shoe with fluid under pressure is realized at the same time in the tubular joint and in the interior chamber of the shoe.

According to a particular embodiment of the invention adapted to be utilized with a band of great width, the chamber fo the shoe is divided into a plurality of elementary chambers each provided with a tubular joint and with feed means for each elementary chamber and the associated joint, each feed means for each chamber being provided with an individual obturation member.

The invention will be described in greater detail with reference to a particular embodiment given by way of example in the annexed drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic elevation view, in section, of apparatus for schematically showing the operation of a flexible joint as utilized between a shoe and a metallic band, b

FIG. 2 shows in simplified fashion apparatus for driving a band according to the invention, and

FIG. 3 is directed to a modification especially applicable to an installation for operating with bands of variable width.

DETAILED DESCRIPTION FIG. 1 is intended to provide an understanding of the principle of a cushion of fluid interposed between two rigid elements moving relative to one another. In FIG. 1 there is seen a plate 20 which supports a load, designated by forces 21, plate 20 facing a surface 22 with repect to which it is to be displaced. The plate 20 is provided at its periphery with an annular hollow joint 24 made of an elastomeric material or of a sheet impregnated with an elastomer such that it is both flexible and capable of resisting internal pressure. The joint 24 defines with the plate 20 an interior chamber 25 into which opens afeed conduit 27 connected to a source of compressed air. At the right of the outlet of a duct 26 leading into the chamber 25, the joint 24 is provided with an orifice 28 which establishes communication between the interior of the joint and the chamber.

Thus when compressed air is injected through the duct 26, the joint 24 is inflated while at the same time the chamber 25 is filled with air. Compressed air escapes from the chamber 25 and forms between the surface 22 and the inflated joint 24 a film of air preventing direct contact of the joint 24 with the surface 22. The leakage flow between the joint 24 and the surface 22 is equal to the feed through the duct 26 while the joint 24 is inflated. There is thus realized a suspension on a cushion of air and it can be determined that the necessary forces to displace the plate 20 on the surface 22 are very low, this being obtained for discharge of air of small magnitude. In addition, if the surface 22 is fragile, the displacement of the plate can be effected without producing scratching of the surface. Finally if the surface 22 is not strictly planar but presents slight waviness, it is found that at the time of displacement of the plate, the material of the joint 24 spontaneously takes a form adapted to the local variations of form of the surface 22 without producing scratches on the surface.

The present invention constitutes one application of this apparatus with a cushion of air having'a flexible skirt to apparatus having a shoe which is the subject of U.S. Pat. No. 3,724,735. This novel application is illustrated in FIG. 2 wherein are seen the same elements essential to the apparatus for driving a band described in the aforesaid patent. Here the band 1 passing in the direction of the arrow successively passes on rollers 2, 3, and 4 which are mounted for rotation on axles carried on a frame 9.

A jack 7 controlled through the intermediary of a distributor 30 connected to a pressure source 8 urges a shoe carrying an inflatable annular joint 24 towards the roller 3. A pressure source 6 connected through the intermediary of a valve 11 feeds compressed air into the chamber in shoe 5 and into the inflatable joint 24. The compressed air reaches a pressure in the interior of the chamber 25 of a value such that taking into account the gap between the surfaces of the shoe and the band, the resultant force of the pressure becomes substantially equal to the force applied by the jack 7, while establishing equilibrium with 'the leakage 'between the joint 24 without which there would be effective contact, all while maintaining the leakage section at a minimum value.

In a given installation, there is generally need to treat bands of diverse widths. The apparatus shown in FIG. 3 is capable of working with bands of different widths. Herein is shown a developed view of the shoe 5 as would be seen by an observer disposed at the axis of roller 3. Here the shoe is provided with 9 flexible joints 24' each being circular and enclosing an interior chamber 25. The arrangement is equivalent to that which has been described above in which the chamber 25 would be divided into a plurality of elementary chambers. As before each chamber 25' and each joint 24' are fed with compressed air by an individual conduit 27' each provided with a valve 32. It is seen that a selective operation of the valves 32 makes it possible to isolate any number of joints to adapt the apparatus to the width of the band, it being understood that it is necessary to avoid straddling the edge of a band by a joint in order not to deteriorate the joint.

It is understood that the invention is not strictly limited to the embodiment which has been described by way of example, but it also covers other embodiments which are only differentiated by variations of execution or by the utilization of equivalent means. Thus while there have been showninflatable joints of circular form it is also possible to provide different closed annular shapes, according to general form of the shoe, with a number of joints to be installed on the shoe.

What is claimed is:

1. in a system for driving a strip comprising a roller for receiving a strip, a shoe movable radially with respect to the roller in the region in which the strip is received, means for injecting compressed air radially inwards of said shoe against said strip, a fixed frame movably supporting said shoe, a jack acting on said shoe in said frame whereby when compressed air is applied between said shoe and said strip on said roller, said strip is applied against said roller with a force equal to that exerted by said jack on said shoe, the compressed air forming a very thin fluid cushion and providing a very small clearance between .said shoe and said strip preventing rubbing of said shoe on said strip, an improvement comprising an annular hollow joint of flexible material on said shoe surrounding a chamber formed in said shoe and into which said compressed air is introduced to applythe strip against said roller, said joint having an orifice which opens into said chamber so that when the chamber ispressurized by the compressed air the joint will simultaneously. be pressurized and inflated.

. 2. An improvement as claimed in claim 1 wherein said shoe has an inlet which opens into said chamber, said orifice in said joint being proximate said inlet.

3. An improvement as claimed in claim 1 wherein said shoe has a concavity defining said chamber.

4. An improvement as claimed in claim 1 wherein a plurality of said joints are mounted on said shoe to define a plurality of individual respective chambers, each chamber having an associated means for feeding compressed air thereto.

5. An improvement as claimed in claim 4 wherein each of the means for feeding compressed air into the individual chambers comprises an obturation valve.

6. An improvement as claimed in claim 1 wherein said annular joint is circular.

7. An improvement as claimed in claim 3 wherein said orifice in said joint faces the surface of the shoe bounding said concavity.

8. An improvement as claimed in claim 4 wherein said plurality of joints are arrayed in two rows. 

1. In a system for driving a strip comprising a roller for receiving a strip, a shoe movable radially with respect to the roller in the region in which the strip is received, means for injecting compressed air radially inwards of said shoe against said strip, a fixed frame movably supporting said shoe, a jack acting on said shoe in said frame whereby when compressed air is applied between said shoe and said strip on said roller, said strip is applied against said roller with a force equal to that exerted by said jack on said shoe, the compressed air forming a very thin fluid cushion and providing a very small clearance between said shoe and said strip preventing rubbing of said shoe on said strip, an improvement comprising an annular hollow joint of flexible material on said shoe surrounding a chamber formed In said shoe and into which said compressed air is introduced to apply the strip against said roller, said joint having an orifice which opens into said chamber so that when the chamber is pressurized by the compressed air the joint will simultaneously be pressurized and inflated.
 2. An improvement as claimed in claim 1 wherein said shoe has an inlet which opens into said chamber, said orifice in said joint being proximate said inlet.
 3. An improvement as claimed in claim 1 wherein said shoe has a concavity defining said chamber.
 4. An improvement as claimed in claim 1 wherein a plurality of said joints are mounted on said shoe to define a plurality of individual respective chambers, each chamber having an associated means for feeding compressed air thereto.
 5. An improvement as claimed in claim 4 wherein each of the means for feeding compressed air into the individual chambers comprises an obturation valve.
 6. An improvement as claimed in claim 1 wherein said annular joint is circular.
 7. An improvement as claimed in claim 3 wherein said orifice in said joint faces the surface of the shoe bounding said concavity.
 8. An improvement as claimed in claim 4 wherein said plurality of joints are arrayed in two rows. 